The present disclosure relates to detecting anomalies in a structure, such as an aircraft or other structure, and more particularly to a method and system for detecting an anomaly, such as a delamination or other defect, and generating an image of the anomaly using backscattered waves.
New, lightweight composite materials and designs are being used more extensively in the aerospace industry for commercial aircraft and other aerospace vehicles, as well as in other industries. The structures using these composite materials may be formed using multiple plies or layers of material that may be laminated together to form a lightweight, high strength structure. Similar to traditional materials, these structures may be subject to extreme stresses, such as during flight operations for aerospace vehicles or other operations, or damage from an impact or other cause. The multiple plies of material can separate or become delaminated as a result of these stresses or impact. As new and traditional materials are being designed in more optimized manner, there is also the need in the aerospace industry to quickly identify and maintain all structures with better efficiency—improving the dispatch reliability and increasing the in-service use of aircraft and any other similar expensive equipment. As such, there is a need to visualize damage or delamination in plate-like structures using permanently attached piezoelectric actuators/sensors. However, such efforts have failed to successfully demonstrate feasibility of actual implementation on real aircraft structures due to heavy dependency on empirical imaging processes based on prior training data and lack of simple but robust interpretation techniques directly relating complex signal responses to true damage information. Previous imaging techniques have only generated qualitative images of damage which were not directly related to the true damage size or outline. Accordingly, a robust imaging technique is needed that can generate a true image of damage equivalent to the one from conventional non-destructive evaluation methods, such as C-scan, x-ray or similar evaluation technique.